We've discussed how wrapping bananas with plastic wrap keeps a bunch fresher longer, but if you want your banans to last as long as possible, the real key is to separate them and then wrap each individual stem with plastic wrap. Here's why.

Instructables user wilgubeast explains that the traditional method of wrapping the whole crown of a bunch works well, but if you want those bananas to last all week, separate them and wrap the stems individually as tightly as possible. You can also slice them up and rest the cut sides in a little acid (lemon juice works best, maybe a little vinegar) to prevent browning. Some people also swear by putting them in the fridge to slow the process.

If you're uncertain of the science here, it's really straightforward. Bananas, like many fruits, release ethylene gas naturally, which controls enzymatic browning and ripening of not just itself, but other fruits nearby. Much of that offgassing takes place at the stem—or the crown—of the banana. By wrapping the crown of a bunch, you slow down the ripening process a bit. For the best effect, separate the bananas and wrap them individually. If you've ever gotten a fresh bunch home and removed the wrap around the crown only to discover the bananas ripened faster than you expected (this has happened to me before), this is why. Still, don't take my word for it, wilgubeast links a number of papers on the topic at the link below, along with more detail on how to wrap those stems.